Place chocolate in food processor fitted with metal blade. Bring cream, corn syrup, and salt to boil in small saucepan (or in microwave); stir to combine. With food processor running, gradually add hot cream mixture through feed tube; process until mixture is smooth, about 1 minute, scraping down bowl once. Add sugar and vanilla; process until combined, about 30 seconds, scraping bowl down once. With machine running, add butter one piece at a time; process until smooth and no butter chunks remain, about 1 minute, scraping down bowl as needed. Transfer to small bowl and let stand at cool room temperature until thick and spreadable, about 30 minutes.

Makes about 2 cups